Most people simply visit a photography studio, ask what shots the photographer would recommend, and then start the session. One of the keys to getting representation and work is to create a powerful composite sheet. You can do this by making your photos look like ads, and by showing a variety of expressions and emotions in the shots that you take. When you shoot a test shot, people should think that it is an ad for a specific product or company. Use props in the shot, but never have a logo or brand name showing.
You can get incredible ideas for how to make the shot look like an ad by spending time in a bookstore and look at lots of magazines. View publications you could imagine seeing yourself in. Study the ads, and let the professionals teach you how to create the photos that are right for your image.
This is a great way to learn and practice creating strong commercial photos. You can read more about this in the 26 pages I devote to this topic in my book, How to Become a Successful Commercial Model.